Estimate your child's predicted adult height using the mid-parent (Galton) method. Enter both parents' heights and the child's sex to get an estimated adult height range. This method is simple and provides a reasonable estimate for most families.
Adult height is approximately 60-80% heritable — meaning genetics is the dominant predictor of how tall a child will be. The mid-parent method, originally developed by Sir Francis Galton in the late 1800s and refined since (often called the Tanner method in modern pediatrics), provides a simple framework for estimating a child's predicted adult height from the heights of biological parents.
The formula: average the parents' heights, then add 2.5 inches for a son (boys are typically taller than their mothers) or subtract 2.5 inches for a daughter (girls are typically shorter than their fathers). This produces a "mid-parental height" estimate, with a typical accuracy of ±2 inches (~5 cm) for about 95% of children. The remaining variation comes from nutrition during childhood, overall health, genetic factors beyond parental height (random recombination, expression of latent height genes), and environmental factors.
This calculator estimates adult height from biological parents' heights and the child's sex. It works at any age (only parental heights are needed). For more refined predictions in older children, pediatricians can use bone-age X-rays combined with current height to identify children whose growth trajectories are likely above or below mid-parental prediction. Important: predicted height is an estimate, not a destiny. Children sometimes exceed or fall short by 3-4 inches due to nutrition, medical conditions, late or early puberty timing, and other factors. The prediction is most useful as a screening tool ("is my child growing as expected?") rather than as a precise forecast.
Father 5'10" (70"), Mother 5'5" (65"). Son. Predicted: (70 + 65 + 5) / 2 = 70" = 5'10" Likely range: 5'8" to 6'0" Matches population average male height (~5'9-5'10"). Son will likely fall close to father's height. Within range encompasses about 95% of likely outcomes.
Father 6'2" (74"), Mother 5'9" (69"). Daughter. Predicted: (74 + 69 − 5) / 2 = 69" = 5'9" Likely range: 5'7" to 5'11" Daughter will likely be tall (above average female height of ~5'4"). Tall heritage tends to produce tall children. Note: there's a small "regression to the mean" effect where children of unusually tall parents tend to be slightly less tall than the mid-parent prediction (and children of unusually short parents tend to be slightly taller), but the effect is small relative to formula uncertainty.
Father 5'6" (66"), Mother 5'9" (69"). Son. Predicted: (66 + 69 + 5) / 2 = 70" = 5'10" Likely range: 5'8" to 6'0" Son's prediction is essentially the average of parents adjusted for male offset. Notice the predicted height exceeds either parent's height — this isn't an error. Genetics combine in complex ways, and a son's predicted adult height is based on the mid-parental average plus the sex offset, which can land outside the range of either parent. Reality: actual height will depend on which specific height-influencing genes the son inherits from each parent, plus environmental factors. Result could be anywhere from ~5'7" to 6'0"+ even within "normal" inheritance.
Use this calculator out of curiosity, when planning pediatric care, when concerned about your child's growth trajectory relative to expectations, or when discussing growth concerns with your pediatrician.
The mid-parent method is the simplest and most widely used height prediction tool. For most families, it provides a useful estimate within ±2 inches.
Pair with bmi-kids (pediatric BMI tracking), ideal-weight calculator (long-term planning), and general growth tracking on CDC charts.
Important practical considerations:
1. **Genetics is dominant but not absolute.** Genetics explains 60-80% of height variation. Nutrition, health, and environment account for the rest. Children sometimes meaningfully exceed or fall short of mid-parental prediction.
2. **Track growth percentile over time.** Single height measurements matter less than the trajectory. A child consistently at the 30th percentile is fine; a child who drops from 50th to 15th percentile within a year warrants pediatric assessment.
3. **Puberty timing affects outcome.** Early puberty (especially in girls) often correlates with shorter adult height because growth plates close earlier. Late puberty often correlates with taller adult height due to extended growth window. Bone age X-rays can identify these patterns.
4. **Nutrition matters during growth windows.** Adequate protein, calcium (1000-1300 mg/day for children/teens), vitamin D, zinc, and overall calorie sufficiency support reaching genetic height potential. Restrictive diets during growth years can permanently reduce adult height.
5. **Chronic conditions affect growth.** Untreated celiac disease, growth hormone deficiency, hypothyroidism, kidney disease, and other conditions can reduce height. Children meaningfully below mid-parental prediction warrant pediatric workup.
6. **Sleep matters.** Growth hormone primarily releases during deep sleep, especially early-night cycles. Chronic sleep deprivation can reduce growth.
7. **Adoption/step-parent situations.** Mid-parent formula uses genetic inheritance. For adopted children, biological parents' heights (if known) are the relevant inputs. Step-parents and adoptive parents' heights don't predict the child's adult height genetically.
8. **Final height vs. growth velocity.** Many parents focus on the destination (final adult height). Pediatricians focus on the trajectory (consistent growth velocity, percentile maintenance). The trajectory matters more for identifying growth disorders.
9. **Regression to the mean.** Children of very tall parents tend to be slightly shorter than mid-parental prediction; children of very short parents slightly taller. This is statistical regression, not a defect — it reflects that height genes recombine and revert toward population averages over generations. Effect is small (~0.5 inches) relative to formula uncertainty.
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5'10" = 70 inches
5'5" = 65 inches
Predicted Height
5'10"
In Inches
70.0"
In Centimeters
177.8 cm
Range
68.0-72.0"
| Detail | Value |
|---|---|
| Father's Height | 5'10" (70 in) |
| Mother's Height | 5'5" (65 in) |
| Child's Sex | Male |
| Formula | (Dad + Mom + 5") / 2 |
| Predicted Height | 5'10" (70.0 in) |
| Predicted Height (cm) | 177.8 cm |
| Likely Range | 5'8" to 6'0" |
| Range (inches) | 68.0 to 72.0 in |